The invention relates to a process for obtaining a single-piece capsule made of a plastic material.
Capsules of the type described above have been in use for some time, as caps for bottle containing water, drinks and liquids in general. These capsules, briefly, comprise a cap for opening and closing the bottle, and a device, generally a security strip, for ascertaining whether a bottle has been opened. The relatively low cost of each of these capsules and the very high number of capsules used lends importance to even a small improvement in their manufacture; indeed, even with a tiny improvement an enormous production saving can be made.
An established manufacturing method for these capsules is press-forming, which consists in introducing a piece of plastic material into the matrix of a die and deforming the material by means of a punch which penetrates the matrix and forces the material to occupy all of the space between the punch and the matrix, which space is obviously in the shape of the finished capsule.
Singlexe2x80x94piece plastic capsules are made in this way, which, in the simplest and most economical versions, can be ready for use as soon as they are formed, while more refined and reliable versions require subsequent work operations. This technology has the advantage that the dies are quite simple and can be used, for example, in rotary machines which comprise a large number of die matrices and punches; these machines are extremely fast and can provide a very high rate of production.
The disadvantage of this technology is that, for manufacturing more refined and more reliable capsules, subsequent work operations are required, which lengthen production times at the expense of production rate, i.e. productivity.
The main aim of the present invention is to suggest a process for manufacturing plastic capsules which reduces production times, and therefore costs, but which at the same time produces highly reliable capsules.
This aim is achieved by the process of the invention, as it is characterised in the appended claims.